Welcome to the Meghalayan era – a new phase in history

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IUGS

The official history of the Earth has a new chapter – and here we are.

Geologists have ranked the last 4,200 years as a distinct age in the history of our planet.

They call it the Meghalayan Age, whose beginning was marked by a mega-drought that crushed a number of civilizations around the world.

The International Chronostratigraphic Chart, the famous diagram illustrating the Earth's history calendar (seen on many walls of the classroom) will be updated.

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IUGS

It must be said, however, that the scientific community is worried about the way in which the change was introduced. Some researchers believe that there has not been enough discussion on this topic since Meghalayan was first introduced in a scholarly article seven years ago.

Geologists divide the 4.6 billion year existence of Earth in time slices.

Each slice corresponds to significant events – such as the breakup of continents, dramatic changes in climate, and even the emergence of particular types of animals and plants.

We are currently living in what is called the Holocene epoch, which reflects everything that has happened in the last 11,700 years – since a spectacular warming has driven us from the last ice Age. But the Holocene itself can be subdivided, according to the International Commission on Stratigraphy (ICS).

He is the official guardian of geological time and he proposed three steps to indicate the upper, middle and lower phases of the time.

They all record major climatic events. The Meghalayan, the youngest stage, extends from 4200 years to 1950. It began with a destructive drought that lasted two centuries and deeply disrupted civilizations in Egypt, Greece, Syria, Palestine, in Mesopotamia, in the Indus Valley and in the Yangtze. Valley of the river.

It was probably triggered by changes in ocean and atmospheric circulation.

The megalayan era is unique among the many intervals of the geological scale in that its onset coincides with a global cultural event produced by a global climate event, says Stanley Finney, a professor of geological sciences at the University of Michigan. State University of Long Beach and Secretary General of the International Union of Geological Sciences (UISG), which has ratified the proposal of the ICS.

The middle phase of the Holocene will be called Northgrippian and will extend from 8,300 years up to the beginning of the Meghalayan. The beginning of this age was a sudden cooling, attributed to large volumes of fresh water from melting glaciers in Canada that flow into the North Atlantic and disrupt ocean currents.

The earliest phase of the Holocene – the release of the Ice Age – will be known as Greenlandic.

To gain a classification, a geological time slice must generally reflect something whose effects were of global extent and be associated with a type of rock or sediment that is clear and unambiguous.

For the famous 66-million-year-old frontier marking the transition period from Cretaceous to Tertiary, this "golden tip" is represented by traces in the sediments of the iridium element. This has been spread across the planet in the debris scattered by the asteroid that has erased the dinosaurs.

For the Meghalayan, the spike is embodied in specific chemical signatures, the best example of which can be seen in the layers of stalagmites on cave soils in the state of Meghalaya northeast of l & # 39; India.

Already the decision to discriminate ages within the Holocene has drawn fire from some scientists who believe that the move is premature. They wonder if some of the climate changes used as anchor points for the new ages have had a truly global impact.

They are also concerned that the divisions were approved when there is still an active debate on the allocation of a new geological time slice to specifically reflect the 39, the influence of humans on the planet.

Tentatively called the Anthropocene, its precise definition – its point of departure and the peak used to designate its initiation – is the subject of ongoing research.

Mark Maslin is Professor of Geography at University College London, UK, and key figure in the discussion on the Anthropocene.

He told the BBC News: "After the original document and going through various committees, they announced suddenly [the Meghalayan] and pasted it on the chart: it's official, we're in a new era, who knew? many new definitions that may now contradict the working group on the Anthropocene and go against what most scientists perceive as the most important change on Earth over the last 10,000 years. "

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